Ethernet technology based on packet switching is increasingly being used by telecommunication operators. It intervenes at the level of the transport layer of the OSI model, the acronym standing for “Open Systems Interconnection”, and replaces transmission in synchronous mode carried out, for example, by way of the SDH protocol, the acronym standing for “Synchronous Digital Hierarchy”.
It is for example implemented by an operator for collecting residential streams in a collection network. Such a network comprises a plurality of access points, which are in particular responsible for collecting the various types of streams which originate from subscribers. When the link is a telephone copper wire pair, the access point is a digital multiplexer of client lines, known by the term DSLAM. DSLAM is the acronym standing for “Digital Subscriber Line Access Multiplexer”.
Ethernet VLAN technology allows an operator to define, on the basis of a physical telecommunications network, several virtual networks, so as to differentiate the services that the operator puts in place for their clients. A virtual or Ethernet VLAN network, the acronym standing for Virtual Local Area Network, connects the terminals involved in the implementation of a particular service.
To facilitate the processing of the various types of streams which pass through the access point, the operator puts in place virtual networks which pertain, for example, to:                a voice-over-IP related service, IP being the acronym standing for “Internet Protocol”;        a television-channels-over-IP service;        a VOD service, the acronym standing for “Video On Demand”;        an Internet access service;        a service offering a first bundle of satellite television channels;        a service offering a second satellite television bundle;        the traffic for managing the collection network proper.        
A first advantage of Ethernet VLANs is that the items of equipment connected by a first Ethernet VLAN are not directly accessible at the Ethernet level from an item of equipment belonging to a second Ethernet VLAN. One speaks of leakproofness between the virtual networks. This leakproofness facilitates the processing of the data streams.
A second advantage of virtual networks resides in the fact that they allow dynamic configuration of the physical transport network so as to accommodate the variable requirements of clients over time. For example, the television-channels-over-IP service may require dynamic bandwidth allocation on a specific day from 20H45 to 23H00 during retransmission of the football world cup final. In this case, an additional Ethernet VLAN may be put in place during this period by the operator to allocate the additional bandwidth. A bank may also ask to benefit from dynamic bandwidth allocation every night to convey data between its headquarters and its branches.
An Ethernet VLAN is identified in the network on the basis of Ethernet level information, more precisely by an identifier field. The IEEE 802.1Q standard defines an identifier field VLAN-ID for representing the serial number of an Ethernet VLAN of Ethernet type. This field is coded on 12 bits and therefore allows 4096 values of Ethernet VLAN serial numbers. For its part, the IEEE 802.1ah standard defines an identifier field I-TAG coded on 20 bits.
When it is decided, for example at the level of a transmission network management system or NMS, the acronym standing for “Network Management System”, to create a new service or to establish new connections within the network, a request is emitted by the NMS, via a management network, destined for entities of the network, called client entities. This request specifies the Ethernet VLAN involved with the aid of its identifier field. The client entities of the transport network which receive the request emitted by the NMS are, for example, routers which then pass on the request to server entities of the transport network, such as access points, so as to establish the requested end-to-end connection.
Increasingly often today, an operator uses Ethernet technology and in particular VLANs to dynamically configure his transport network.
The quantity of information relating to the VLAN identifier fields to be conveyed between the NMS and the client entities of the transport network is constantly growing. This is because the creation of a new service may require the specification of several hundred VLANs. The putting in place of an interconnection of metropolitan networks based on Ethernet technology by a transport network or an aggregation of network services in a lower layer, for example an aggregation of Ethernet VLAN virtual networks in an SDH transport layer, may be mentioned for example.
Now, current protocols for managing VLANs allow the specification of only a single VLAN serial number per request. Consequently the creation of a new service may require the sequential dispatching of several hundred requests.
Though the management network through which the request for a new service or new connection travels has a significant bandwidth and therefore imposes only few constraints in terms of throughput, such is not the case for the transport network for which the load caused in terms of throughput is increasingly significant.